Method for making composite foamed plastic containers



Oct. 4, 1966 c. E. PLYM'ALE ET AL 3,277,220

.METHOD FOR MAKING COMPOSITE FOAMED PLASTIC CONTAINERS 4 Sheets-Sheet 1Original Filed Jan. 5, 1961 FIG. 2

FIG. I

INVENTORS C. E. PLYMALE CARLTON A. RICHIE BY ATTORNEYS Oct. 4, 1966 c.E. PLYMALE ET A METHOD FOR MAKINGQGOMPOSITE FOAMED PLASTIC CONTAINERS 4SheetsSheet 2 Original Filed Jan. 5, 1961 ATTRNEYS Oct. 4, 1966 c. E.PLYMALE ET AL 3,277,220

METHOD FOR MAKING COMPOSITE FOA MED PLASTIC CONTAINERS 4 Sheets-Sheet 5Original Filed Jan. 5, 1961 FIG. 9

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INVENTORS C. E. PLYMALE CARLTON A. RICHIE ATTORNEYS Oct. 4, 1966 c. E.PLYMALE E L 3,277,220

METHOD FOR MAKING COMPOSITE FOAMED PLASTIC CONTAINERS Original FiledJan. 5, 1961 4 Sheets-Sheet 4.

FEGEE INVENTORS J C E. PLYMALE CARLTON A. RICHIE United States Patent3,277,220 METHOD FOR MAKING COMPOSITE FOAMED PLASTIC CONTAINERS CharlesE. Plymale, Maumee, and Carlton A. Richie,

Toledo, Ohio, assignors to Owens-Illinois Glass Company, a corporationof Ohio Original application Jan. 3, 1961, Ser. No. 80,382. Divided andthis application Feb. 4, 1963, Ser. No.

3 Claims. (Cl. 26445) This application is a division of our copendingapplication Serial No. 80,382, filed January 3, 1961, now abandoned.

This invention relates generally to the molding of plastic articles,such as containers, bottles, and jars, consisting of at least twoplastic layers of different densities and having improved properties.More specifically, the present invention is directed to plasticcontainers having a dense, smooth, plastic layer integrally bonded to acellular or foamed layer of plastic beads, and to methods for making thesame.

' The use of plastic containers for packaging various cosmetic andmedicinal liquids and creams is well known. By way of example, the useof squeeze bottles made of a plastic such as polyethylene has provenvery satisfactory and has gained wide acceptance. However, for certainpurposes, such as the merchandising and sale of a cosmetic or coldcream, custom has created the demand for a relatively thick-walled,rigid container or jar, and although such a jar could very well be madeor cast of solid polyethylene, not only does the cost of such acontainer per se rise sharply, but also the expense incident to shippingthe same.

The use of glass for cold cream jars is well known for such purpose, buta glass jar is quite fragile and subject to being dropped and broken, inaddition to being relatively heavy. Accordingly, it would be highlydesirable in the packaging art to provide a jar which would be neitherfragile, like glass, nor unduly expensive, as a solid plastic articlewould be, and yet relatively light in weight when compared with similararticles made from either glass or solid plastic. Such light weightcontainers would facilitate handling besides resulting in substantialsavings with respect to the cost of shipping the containers.

It is, therefore, an object of this invention to provide a noveleconomical method of molding plastic container which is not fragile,consisting of two or more plastics of different densities.

Another object of this invention is to provide a method of molding aplastic container consisting of two or more plastics of differentdensities, wherein the plastics are integrally bonded and interlockedtogether.

A further object of this invention is to provide a method of molding acontainer which is easier to handle and less expensive to ship due toits lightness.

Still another object of this invention is to provide a method of moldinga plastic container which is lighter in weight than a container made ofglass or a solid plastic.

According to the present invention, it has been discovered that plasticcontainers can be satisfactorily obtained by employing a relativelyimpervious, dense and solid plastic layer, such as polyethylene, as aliner and binding thereto a continuous but relatively pervious cellularor formed layer of expanded plastic beads, such as cellular polystyrenebeads.

Other objects and advantages of the foregoing invention will become moreapparent from the following detailed description taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is an elevational view, partly in section, of the 3,277,220Patented Oct. 4, 1966 liner employed in the making of a cosmetic jar inaccord ance with the present invention;

FIG. 2 is a sectional view of the completed jar, using the liner of FIG.1 which is shown partly in elevation and section;

FIG. 2a is an enlarged fragmentary sectional view of the area of contactbetween the liner and layer of expanded plastic beads;

FIG. 3 is a sectional view of the lip or finish area of a container ofmodified construction;

FIG. 4 is a sectional view of a modified construction;

FIG. 5 is a sectional view of a further modified construction;

FIG. 6 is a sectional view showing a molding apparatus suitable formaking the article of FIG. 2;

FIG. 7 is a sectional view of the mold apparatus of FIG. 6 in closedposition;

FIG. 8 is a sectional view of the apparatus of FIG. 7 upon completion ofthe molding cycle;

FIG. 9 is a sectional view showing a molding apparatus suitable formaking the article of FIG. 4;

FIG. 10 is a sectional view of the mold apparatus of FIG. 9 in closedposition;

FIG. 11 is a sectional view of the apparatus of FIG. 10 upon completionof the molding cycle;

FIG. 12 is a sectional view of a modified form of a liner and matchingouter layer;

FIG. 13 is a sectional view of the elements of FIG. 12 in assembledform; and

FIGS. 14, 15 and 16 are sectional views of apparatus suitable for makingthe article of FIG. 13.

Referring to FIG. 2, jar 1 is a representative container of the presentinvention, consisting of the plastic liner 2 shown in FIG. 1 and whereinthe liner 2 is completely encased by a cellular mass or layer 3 ofexpanded plastic beads. It will be noted that where the expanded plastichas been removed from the inner liner, as shown in FIG. 2, there hasbeen imparted to the surface of the liner adimpled effect which has thesalutary effect of serving as an interlocking means to bond the liner 2to the overlying cellular plastic mass 3.

The novel containers of FIG. 2 can be made in a number of ways, andsuggested apparatus for making these containers is disclosed in FIGS. 6,7 and 8. By way of example, the liner 2, which can be preformed byplastic sheet shaping apparatus well known in the art, is mounted on aforce plug 11 of the same size and configuration as shown in FIG. 6. Thelower mold cavity '12, which is defined by force plug 11 mounted on ram19 and spring mounted tube 13, is then partially filled with a measuredamount of expandable polystyrene beads P. The split female mold members14 and 15 are then brought into a closed position by r-ams 16' and 17,respectively, and force plug 11 is caused to move upward and assume theposition as shown in FIG. 7. Due to the bead nature of the moldingmaterial plus the coa'ction of plug 11, sleeve 12, and mold members 14and 15, a uniform distribution of the beads will take place.

Steam then enters the heating coils 18 embedded in the walls of the moldcavity, and causes the plastic beads to coalesce and expand into acellular mass which becomes firmly bonded to the plastic liner 2. Uponcooling, the mold is opened as shown in FIG. 8, and the completed jar isremoved. The bonding between the liner 2 and cellular mass 3 isessentially mechanical in nature, since the plastic beads, uponexpanding, form rounded projections which project into the liner to formindentations. These projections and indentations match and complementeach other so as to form a strong mechanical interlock. Of course, inthe preferred method the liner is one which softens on the applicationof heat in the expansion step.

' (FIG. 13).

Polyethylene is one preferred material for the liner. The spring inFIGS. 6-8 merely aids in retraction of ram 19 and can be omitted.

From the foregoing description, it will be apparent that one method ofmanufacturing the novel article of FIG. 2 of the present invention,wherein the liner is internally positioned, has been disclosed. However,to those skilled in the art, other methods of preparing these articlescould be employed in which other types of apparatus would be involved.

Although the example above stresses the use of a liner coated with athick layer of expandable plastic beads, it is apparent that for certainpurposes the reverse construction may be desired. For example, in FIG.4, there is shown a modification in which the container 1 has theexpandable plastic 3 positioned on the inside and the plastic liner 2now becomes a coating. Apparatus suitable'f-or making the article ofFIG. 4, wherein the liner is externally positioned, is shown in FIGS. 9,and 1-1.

The first step in making the article of FIG. 4 consists in positioningliner 2' within a mold cavity 21 of female mold member 22. Thereafter,liner 2' is filled with a measured amout of expandable plastic beads P,as shown in FIG. 9, so as to form the ,proper thickness of expandableplastic bead layer in the subsequent molding step.

Force plug 23 then enters the mold cavity 21 and, when the plug reachesthe position shown in FIG. 10, air enters channel 25 and exits throughopening 26 into the cavity defined by plug 23 and mold 22, therebycausing a distribution of the plastic beads within this cavity. When theforce plug 23 reaches its lowermost point, a heating fluid is thenintroduced into a channel 24 within plug 23 so as to expand and coalescethe expandable plastic as shown in FIG. 11. Upon cooling, the mold isthen opened and container 1 is removed.

It will also be obvious to those skilled in the art that the two moldingsteps shown by FIGS. 6-8 and 9-11 could be combined whereby a plasticliner not only covers the force plug but the mold cavity. Thereafter, aprescribed amount of expandable plastic beads is introduced into themold cavity, the mold is then closed, and heat is applied so as toobtain the finished container 1" of FIG. 5, which has plastic liners 2"and 2" enclosing the expandable plastic 3". Still other modificationscan be made. In FIG. 1, the liner 2 is shown as coming to the very endof the mouth of the jar. However, for certain purposes, it is desirableto have the liner end just short of the mouth of the jar so that thethreaded lip area or finish of the jar will be made entirely of theexpandable plastic beads, as shown by FIG. 3.

It is to be understood that although the type of mechanical interlockshown in FIG. 2, wherein the liner is indented by the beads of the outercellular layer, is preferred, other expedients can be employed to causethe liner and cellular layer to adhere to one another. For example, aglue or adhesive can be used which can be applied to the inside of apreformed liner, which is then inserted onto a matching preformed innercellular layer to form an article similar to FIG. 4 except for thepresence of a thin layer of glue between the inner foamed plastic layer3' and liner 2'.

Other examples of a plastic cellular layer mechanically interlockingwith a plastic liner include the use of a matching cellular plasticlayer and liner, which are preformed with such close tolerances thatthey can be pressfit together to form an integral article similar toFIG. 4. Moreover, the liner 2 and outer match-ing cellular plastic layer3" can be made with a protuberance or bead 38 and an indentation orgroove 37, respectively (FIG. 12), which are in alignment when the lineris firmly seated in the outer layer thereby forming an integral article1" One apparatus which can be used to make layer 3" is shown in FIGS.14, 15 and 16.

Referring to FIG. 14, a molding apparatus (in open position) is shown asconsist-ing essentially of a reciprocable upper female mold 31 havingopenings 35 for the introduction of heating and cooling fluids, andhaving a cavity 36 corresponding to a lower male mold plug 32.Surrounding the mold plug is a loading tube 33 mounted on springs 34.

At the beginning of the molding operation, as illustrated by FIG. 14, ameasured amount of expandable plastic beads, such as polystyrene beads,is placed in the top of the mold plug 32. More specifically, the beadscan be said to have been placed in an open lower mold structure orcavity of varying capacity and contour whose boundaries are defined byplug 32 and loading tube 33. Some of the beads will fall down into thecrevice between the plug 32 and the loading tube 33, but most of themwill be retained in a pile on top of the plug. When the upper mold islowered, it will first contact the loading tube and gradually force itdownward. As the loading tube retracts, the beads piled on the end ofthe plug will fall down into the space formed between the mold plug andfemale mold cavity. As the mold cavity reaches its lowest position, asshown in FIG. 15, a complete uniform distribution of the plastic beadsoccurs due to gravity and cooperative action of the mold parts.

From the foregoing, it will be evident that the loading tube cooperateswith the mold plug to form a receptacle or reservoir of varying contourand capacity for the retention and distribution of the beads. Heat isthen applied by injecting steam into openings 35 of mold 31,

which in turn heats the plastic beads P causing them to expand and fusetogether. After the container is formed, the mold is permitted to cool,and mold 31 is then raised which results in the loading tube returningto its extended position. In so doing, it will force the moldedcontainer off the mold plug. If desired, a channel (not shown) can bedrilled in plug 32, which would terminate at the top surface of theplug. By connecting a source of air under pressure thereto, which is anexpedient well known in the art, the finished article could be jetejected from the final molding station.

It is also apparent that the resulting article illustrates severaladvantages over known articles used for the same purpose. For example,the present article is very resistant to mechanical shock and is notsubject to breaking upon being dropped as similar shaped containers ofglass .would. Moreover, although the container is thick walled,

a considerable saving of plastic has been obtained by using expandedplastic beads as the outer covering or lamina. Furthermore, thecontainer of this invention is lighter in weight than similar articlesmade of solid plastic or glass.

In addition, the use of the plastic beads has resulted in the formationof a strong mechanical interlock between the inner liner and the outerplastic beads which, upon being heated in the molding process, werecaused to exmits the ready aflixing of suitable labels, printed matter,

or colored ornamental patterns. Although the outer surface of this layeris smooth, the individual beads, which have been fused together, arestill discernible to the naked eye. As a result, the plastic layer,which consists of foamable plastic beads fused together, is permeable toair and most vapors due to the presence of minute passages between theinterstices of the closely packed and fused beads. This is in contrastto the plastic liner which is substantially impervious.

It will be evident that various plastic liners can be employed of whichpolyethylene, polystyrene, and polypropylene are representative.

One method of making the liners employed in the present invention is setforth in U.S. Patent No. 2,910,728 (see 2" of FIG. 12). In

addition, expandable plastic beads other than the expandable polystyrenebeads referred to above can be employed.

A particularlysuitable polystyrene plastic is that designated as Dylitewhich is in the form of beads and made by the Koppers Company, Inc.These beads can be given a pro-expansion treatment by heating them at180-240 F., very often in the presence of live steam, until a densityof, say, 2-15 lbs. per cubic foot is obtained. The beads inserted intothe molding apparatus in the method of the invention are usuallypartially pre-expanded, but they can also be beads which have receivedno pie-expansion treatment. These polystyrene beads contain a volatileliquid, pentane, as an expanding agent. However, particulate polystyrenecontaining any volatile liquid expanding agent or containing one of thesolid chemical expansion agents which decompose to yield a gaseousexpansion agent on heating can be employed. Although a polymer ofstyrene is preferred, any thermoplastic containing such a volatileliquid or solid chemical expansion agent, giving it the capability ofbeing foamed upon the application of heat, can be used in the method ofthe invention. Of course, the apparatus of FIGS. 6-8 and 9-11 can beemployed to prepare the preformed cellular plastic layer such as 3" ofFIG. 12 by using a mold of appropriate configuration.

While we have described and illustrated preferred embodiments of ourinvention, we wish it to be understood that we do not intend to berestricted solely thereto, but that we do intend to cover allmodifications thereof which would be apparent to one skilled in the artand which come within the spirit and scope of our invention.

We claim:

1. The method of forming a composite integral thermoplastic relativelyrigid container for packaging a product, said container including asolid dense relatively flexible thermoplastic liner having an innersurface and an outer surface and a continuous cellular layer of expandedand fused plastic beads, said layer being substantially thicker thansaid liner, said method comprising the steps of placing one of saidsurfaces of said thermoplastic liner, having said one surface in itsultimate configuration, into entire contact with a mold member of anopened two-part mold having two mold members forming when closed a moldcavity, said contact being with the molding surface of said mold member,thereafter covering at least in part the other of said surfaces of theliner with expandable plastic beads, then providing relative movementbetween the two mold members to close the mold, the amount of beadsbeing sufficient for the beads to be uniformly distributed throughoutthe closed mold cavity,

applying sufficient heat to said plastic beads to expand and partiallyfuse said beads whereby said expanded beads indent the thermoplasticliner where the liner is contacted by the plastic beads and therebythere is formed an integral interlocking of the thermoplastic liner withthe cellular layer of expanded plastic b-ezds, cooling the resultantproduct, opening the mold, and removing the product from the openedmold.

2. The method of claim 1 in which the liner is positioned internallywith respect to the cellular layer of expanded beads by placing theinner surface of the liner in contact with one of said mold members andthe outer surface of the liner is the surface covered with theexpandable plastic beads and in which the composition of the liner ispolyethylene.

3. The method of claim 1 in which the liner is positioned externallywith respect to the cellular layer of expanded beads by placing theouter surface of the liner in contact with one of said mold members andthe inner surface of the liner is the surface covered with theexpandable plastic beads.

References Cited by the Examiner UNITED STATES PATENTS 1,810,896 6/1931Grubman 264-249 XR 2,149,991 3/1939 Dodge 156-294 XR 2,150,910 3/1939Chaplin 229-15 XR 2,591,578 4/1952 McNealy et al. 2,753,642 7/ 1956Sullivan 264- XR 2,950,505 8/ 1960 Frank 264-45 2,951,260 9/1960Harrison et al. 264-53 XR 2,977,639 4/1961 Barkhuff et al. 2,989,783 6/1961 Slapnik 264-45 3,002,640 10/ 1961 Kline. 3,007,594 11/1961 Wallace.3,013,922 12/1961 Fisher 264-45 3,042,967 7/ 1962 Edberg 264-53 FOREIGNPATENTS 497,226 11/ 1950 Belgium.

582,122 8/1959 Canada.

675,765 2/1930 France.

323,759 1/1930 Great Britain.

596,847 8/1959 Italy.

ALEXANDER H. BRODMERKEL, Primary Examiner.

ROBERT F. WHITE, Examiner.

P. E. ANDERSON, Assistant Examiner.

1. THE METHOD OF FORMING A COMPOSITE INTEGRAL THERMOPLASTIC RELATIVELYRIGID CONTAINER FOR PACKAGING A PRODUCT, SAID CONTAINER INCLUDING ASOLID DENSE RELATIVELY FLEXIBLE THERMOPLASTIC LINER HAVING AN INNERSURFACE AND AN OUTER SURFACE AND A CONTINUOUS CELLULAR LAYER OF EXPANDEDAND FUSED PLASTIC BEADS, SAID LAYER BEING SUBSTANTIALLY THICKER THANSAID LINER, SAID METHOD COMPRISING THE STEPS OF PLACING ONE OF SAIDSURFACES OF SAID THERMOPLASTIC LINER, HAVING SAID ONE SURFACE IN ITSULTIMATE CONFIGURATION, INTO ENTIRE CONTACT WITH A MOLD MEMBER OF ANOPENED TWO-PART MOLD HAVING TWO MOLD MEMBER FORMING WHEN CLOSED A MOLDCAVITY, SAID CONTACT BEING WITH THE MOLDING SURFACE OF SAID MKOLDMEMBER, THEREAFTER COVERING AT LEAST IN PART THE OTHER OF SAID SURFACESOF THE LINER WITH EXPANDABLE PLASTIC BEADS, THEN PROVIDDING RELATIVEMOVEMENT